BEWARE of Jiangsu Daao Optoelectrical !

Hi guys,
Wanted to warn you not to buy anything from

Grace Jin
Jiangsu Daao Optoelectrical Co.,Ltd. (Factory)
Add: No.288 Huaqiao Town ,Kunshan of Jiangsu Province 215332 China
Tel:+86-512-57972027
Mobile: +86-13671701504
Email: jsdaao@gmail.com
MSN : zhangfan800512_vip@hotmail.com
Skype: kathyzhang998
Website: Frontpage--Jiangsu Daao Optoelectrical Ltd

Here's my story, I contacted them about buying 1200 lasers with exact specifications - fixed focus, dot diameter <0.5mm at a distance of 150mm. They said that they can manufacture such lasers at 2.9$/piece and offered 4 samples for 125$. After I made the payment, here's what I received:









The quality appears to be extremely poor.
1. green lasers came with the V+ wire not attached, it was just laying next to the laser. connecting it to any of the soldering pads did not work.
2. one of the red lasers looks used and is missing some threads, but also produces a very weak dot, about <1mw, and 2mm in diameter.
3. the second red laser produced a very poor-shaped dot, about 2-3mm in diameter.

Of course, the seller stopped communicating.

BTW, such laser modules retail on aliexpress for 2.5$/piece.

The greens may be Case-Positive, so try connecting the + supply to the exposed brass housing of the module.

They sure ripped you off on that sample price, my condolences. I'm curious how the lens is even in the module with the missing threads, normally it is a threaded lens holder that screws into the module.

You can probably get a ton of cheap 5mW red modules from eBay or aixiz (I seem to remember a member on here having a ton of them too, one of the vets) and manually focus them all to your desired spot size at desired distance. 0.5mm @ 15cm doesn't strike me as unreasonable.

Thanks for the input.
You're right! The green lasers work great then V+ is connected to the case, and not only can they be focused, but they also have great focus depth!

I'm curious how the lens is even in the module with the missing threads

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There are a few threads left at the very begging, so they are holding the lens in a pressed down position.

You can probably get a ton of cheap 5mW red modules from eBay

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One thing I forgot to mention is that I also need good focus depth, which this cheap modules do not provide.

Yet the green ones are pretty cool, maybe you know a honest supplier, who sells them?

Thanks )

How were they offering 2.9$ a piece, then charging $125 for 4 samples. Am I missing something? Are samples not supposed to be free, or at least cheaper than retail? I must be misunderstanding.

Try ebay seller tech hood. Many of us buy from him with confidence. I know he has bulk deals on red modules. Just need to talk to him about specs

How were they offering 2.9$ a piece, then charging $125 for 4 samples.

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Well, their story was that they need to manufacture this samples first. Some seller offered samples for 20$, some even gave them for free, but their end price was about 7-8$/pc, which is a bit over my budget/

Try ebay seller tech hood.

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Thanks, I'll look into him.

By the way, maybe you guys know, what is responsible for focus depth? Why this cheap red ones have it just about a centimeter, while the green one has it over 10 cm?

It has to do with the beam diameter out of the laser (the DPSS green has a much smaller beam), lens focal length, and lens diameter.

dude just go with CNI you will for sure get the quality and specs on not just a handful of your modules but on most if not all of them plus at that quantity they might give you a pretty good discount Green laser, Blue laser, Infra Red laser, IR laser, UV DPSS laser. Here is an example in the current group buy for yellow lasers they have offered a discount for 10 pcs. the original price was $10.5 per mW at 80mW with the discount the price is down to $8.125 per mW that saves people $190 with your large order I am pretty sure you could get a nice discount.

Blackwolf said:

dude just go with CNI you will for sure get the quality and specs on not just a handful of your modules but on most if not all of them plus at that quantity they might give you a pretty good discount Green laser, Blue laser, Infra Red laser, IR laser, UV DPSS laser. Here is an example in the current group buy for yellow lasers they have offered a discount for 10 pcs. the original price was $10.5 per mW at 80mW with the discount the price is down to $8.125 per mW that saves people $190 with your large order I am pretty sure you could get a nice discount.

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Thanks, I dropped them an email. )

Aha, learned about beam divergence! :wave: Sorry I did not know it earlier.

Just to be sure I got it right... if I have a 0.5mm spot at a distance of 150mm and the laser has 1mrad divergence, then according to this calculator ( pseudonomen137's JScript Diameter Calculator ), the beam size at 250mm would be 0.6mm , correct?

Kinda strange, as all the "high quality" laser samples that I've got seem to have the divergence of about 9-10mrad, which is bad, right. As their focus depth is pretty shallow - 0.5mm at 150mm and already about 1.5mm at 250mm.

Thanks )